1. Field of the Invention
This invention relates to a process for deburring moulded parts produced by pressing, especially large edge contours of poorly heat-conducting materials, such as crushed, glued organic raw- or secondary raw materials, for example, which are used to form compressed lignocellulose fibre mats.
2. Description of the Prior Art
Panels, parts of furniture, transport pallets and the internal linings of motor vehicle interiors are produced of fibre mats generally by hot-compressing a voluminous loosly binded fibre mat with press tools giving a three-dimensional self supporting moulded part.
During pressing the edge contour of the moulded part is formed mainly by squeezing or dipping edges thereby producing an outer circumferential waste shoulder which has to be cut off after the finished moulded part is removed from the press tools. Due to the tolerance of the tools and especially due to the wear of the tools caused by producing a larger quantity, a press burr will remain on the finished moulded part after the waste shoulder is cut off which has to be removed during additional working steps. The moulded parts are of voluminous size and;. Therefore the deburring of the press burr was previously made by hand because an automatic deburring cannot be realized by reason of the relatively large moulded parts and their three dimensional shaped, intricate contours. This deburring by hand leads to high production costs, particularly, because the moulded parts themselves are to a large extent manufactured automatically. Hence, it is desirable to reduce the costs attendant the deburring in a way which corresponds to the automatic manufacture of the moulded parts.
Automatic deburring processes are known, such as drum deburring, chemical deburring and thermal deburring, which are used for smaller moulded parts of metallic materials. Dut to the large size of the moulded parts under discussion and their material structure these known deburring processes cannot be used. The moulded parts produced of fibre mats have such a size that it is not possible to place them in a deburring drum. Chemical deburring processes are not applicable due to the liquid receptivity of the fibre materials used to form the discussed moulded parts. The thermal deburring usually used for metallic moulded parts can in particular not be used for pressed organic materials for several reasons. The moulded parts produced of fibre mats are of such size that a suitable apparatus is not available. During thermal deburring in the deburring chamber, pressures of more than 100 bar occur so that the manufacture of apparatus of suitable size is extremely expensive and requires a larger amount of construction work. Moreover, the poor heat-conduction of organic materials prevents the burr from being over-heated with respect to the body of the finished moulded part, as is necessary for the thermal deburring so that the total surface of moulded parts formed of such organic materials are attacked during thermal deburring. This leads to partial cabonization and to formation of cracks, especially, if the wall thickness of the moulded parts is small. The moulded parts thus become useless.
The intent of the invention is to improve the known thermal deburring such that the finished moulded part after pressing can be removed without burrs from the press tools so that the reworking with excessive labor cost hitherto required becomes superfluous.